Apparatus for manufacturing ceramically bonded shaped bodies from granulates of inflatable mineral material

ABSTRACT

An apparatus for manufacturing ceramically bonded shaped bodies from granulates of inflatable mineral materials, particularly clay, which comprises a combustion chamber including two combustion chamber regions tapered down in opposite directions. A fire box is provided which has a bottom grate and is adapted to be filled with granulates of inflatable material. A mount is arranged for the fire box in substantially the plane of the joint largest cross-section of the combustion chamber and movable through the latter. A conduit system is connected to both ends of the burning chamber for guiding fuel - and reaction - gases in a circuit. At least one burner device is disposed in the circuit. A reversing device for reversing the flow of the gases through the combustion chamber is provided. The mount comprises a pocketshaped enlargement open to the axis of the chamber for reception of the fire box in the combustion chamber. The fire box engages the enlargement with an annular outer holding - and guide frame, the latter being covered in the pocket-shaped enlargement against the effect of the heat - and reaction - gases and being connected with a divided heat-shield device limiting laterally the filling space of the fire box by arms limiting the heat flow.

United States Patent 1191 Sundermann 1451 Mar. 12, 1974 1 APPARATUS FOR MANUFACTURING CERAMICALLY BONDED SHAPED BODIES FROM GRANULATES OF INFLATABLE MINERAL MATERIAL [75] Inventor: Erich Sundermann,Braunschweig,

Germany [73] Assignee: Firma Zytan Thermochemische Veriahrenstechnik, Braunschweig,

Germany [22] Filed: Nov. 9, 1972 21 App1.No.: 305,149

[30] Foreign Application Priority Data Nov. 10,1971 Germany .1 2155933 [52] U.S. Cl 432/96, 432/27, 432/215 [51] Int. CL. F27b 1/00, F27b 1/12 [58] Field of Search... 432/13, 96, 27, 180, 215, 0 432/120 5 6 References 1 Cited UNITED STATES PATENTS 3,618,227 11/1971 Brcakell et a1 34/164 2,601,102 6/1952 Dickey.. 432/27 3,538,060 6/1971 Hermans 432 122 3,630,501 12 1971 Shabaker 432 27 2,590.090 3/1952 DeVaney 432 13 Leffer 432/215 Primary Examiner-John J. Camby Assistant Examiner-Hcnry C. Yucn Attorney, Agent, or Firm-Ernest G. Montague 5 7] ABSTRACT An apparatus for manufacturing ceramically bonded shaped bodies from granulates of inflatable mineral materials, particularly clay, which comprises a combustion chamber including two combustion chamber regions tapered down in opposite directions. A fire box is provided which has a bottom grate and is adapted to be filled with granulates of inflatable mate rial. A mount is arranged for the fire box in substantially the plane of the joint largest cross-section of the combustion chamber and movable through the latter. A conduit system is connected to both ends of the burning chamber for guiding fuel and reaction gases in a circuit. At least one burner device is disposed in the circuit. A reversing device for reversing the flow of the gases through the combustion chamber is provided. The mount comprises a pocket-shaped enlargement open to the axis of the chamber for reception of the fire box in the combustion chamber. The tire box engages the enlargement with an annular outer holding and guide frame, the latter being covercd in the pocket-shaped enlargement against the effect of the heat and reaction gases and being connected with a divided heat-shield device limiting later- 7 13 Claims, 7 Drawing Figures 1 APPARATUS FOR MANUFACTURING The present invention relates to an apparatus for the manufacturing of ceramically bonded shaped bodies from granulates of inflatable mineral material, particularly clay, consisting of a combustion chamber which is preferably tapered in opposite directions and has a holding device for a fire box which is movable through the combustion chamber and provided with a bottom grate, located in the plane of the common maximum cross-section of the chamber, and of a system of conduits connected to the two ends of the combustion chamber for the circulated heating and reaction gases, in which circuit there are provided at least one burner device, and a circulating and possibly a reversing device for reversing the direction of flow of the gases through the combustion chamber.

In the known apparatus of this type, the fire box consists of solid side walls having a bottom grate, as well as a cover which is either perforated upon use in the flow chamber or solid upon use outside the flow chamber. In order to obtain ceramically bonded shaped bodies of fine, uniform structure throughout, it is necessary to achieve as uniform as possible an action on the granulates by the heated gases both during the inflation and the ceramic bonding. The temperatures for the inflating and for the obtaining of the ceramic bonding lie within a range of r 1 000 to 1200C. The duration of the time of action as well as the speed and composition of the heating and reaction gases depend on the initial properties of the inflatable material used and on the mechanical and physical properties required for the finished shaped body. These said factors can be varied only within relatively narrow limits. These possibilities of variation are limited in the known apparatus, since it is extremely difficult to subject all granulates contained in a fire box to the same treatment by the gases. Considerable problems arise, particularly in the vicinity of the bottom and walls of the first boxes, since the walls and the bottom of the fire box are on the one hand subjected to the action of the heating and reaction gases, while on the other hand they are subjected to an interaction withthe heated material being fired. As a result of the high temperatures in the combustion chamber and the alternating temperature stresses, one is extremely limited in the selection of the materials which can be used for the fire box.

The invention is based on the discovery that it is not sufficient to use materials of high temperature resistance such as cobalt steels or chrome-nickel steels of high chrome-nickel content for the manufacture of the fire box, but that additional measures are necessary in order to obtain the stability and invariable nature of the dimensions of the fire box under the high alternating thermal stresses.

It is one object of the present invention to provide an apparatus for manufacturing ceramically bonded shaped bodies from granulates of inflatable mineral material which forms an economic solution and which takes into account the difficulties of manufacturing and processing high-temperature steels, the solution being characterized by the fact that the apparatus has, for receiving of the fire box in the combustion chamber, a widening which opens in pocket shape towards the axis CERAMICALLY BONDED SHAPED BODIES FROM I of the chamber and into which an annular, outer supporting and guide frame of the fire box engages, the frame being shielded within the pocket-shaped widening by the latter from the action of the heating and reaction gases and being connected via arms limiting the heat flow with a subdivided heat protection shield which limits the filling of the fire box laterally.

It is another object of the present invention to provide an outer supporting and guide frame of a material which is not of high temperature resistance, since it is arranged in the combustion chamber in a manner substantially protected from the heating and reaction gases, so that only the protective shield which laterally delimits the filling space of the fire box need be made of material of high temperature resistance. The protected arrangement of the supporting and guide frame as well as the divided development of the protective shield result in the fact that warping of the fire box is avoided despite the high temperatures acting on the material.

The protective shield preferably consists of a cobalt steel containing more than 50 percent cobalt. This alloyhas the advantage over chrome-nickel steel of very high chrome-nickel content that it is more resistant to abrasion and has less affinity for the material which is to be inflated.

The outer supporting and guide frame is preferably made of a steel casting with spheroidal graphite which contains no other alloy components.

7 The pocket-shaped broadening for the receiving of the fire box is preferably equipped with heat dissipation surfaces, which may suitably be connected to a cooling system. In this way the result of a controlled heat flow from the heat shield can be obtained, so that the shield always remains at a temperature of 20 60C below the temperature of the grandulates (between 1000 and 1200C, depending on the material), while the supporting frame in the pocket-shaped broadening of the com-' bustion chamber can be maintained at a temperature of means can also be provided.

The space between the heat shield, which consists generally of a plurality of individual shield plates arranged so as to form gaps and supported on the supporting and guide frame, and the inside of the supporting and guide frame is filled with a heat-insulating material.

The bottom grate of the fire box may suitably consist of a bar grate in which the grate bars may be developed as individual bars, grate elements or of a structural unit, they being supported on the heat shield. In this connection, a ratio of perforated grate surface to total bottom surface of the fire box of between 0.26:1 and 0.46:1, and preferably between 0.36:1 and 0.40:1, has proven advantageous in actual practice. The temperature of the grate with such a ratio is maintained at values which correspond to the temperature of the heat shield.

with these and other objects in view, which will be apparent in the following detailed. description, the present invention, which is shown by example only, will be clearly understood in connection with the accompanying drawings, in which:

FIGS. la, 1b and 1c are schematic, vertical sections of the apparatus of the present invention, partially in side elevation; t

FIG. 2 is on a larger scale a section through the edge region of the fire box of the present invention;

FIG. 3 is a top plan view of a part of the edge region of FIG. 2; and

FIGS. 4 and 5 are plan views in accordance with FIGS. 2 and 3 of another embodiment of the present invention.

Referring now to the drawings and in particular to FIGS. 1a to 10, the apparatus consists of a combustion chamber 1 and a regenerator 2, the latter being arranged in a main circuit 3 forcirculated fuel gases and the combustion chamber 1 being arranged in a parallel circuit 4 for the combustion gases, the parallel circuit being connected to the regenerator 2.

The combustion chamber 1 consists of two chamber sections 5 and 6 which taper in opposite directions and by which combustion chamber regions 7 and 8 are formed. In the plane 9 of the common largest crosssection of the combustion chamber, a mount is provided for a fire box 13 having a bottom grate 16 and filled with granulates of inflatable material. The mount consists of a ring-shaped pocket 12 which lies outside the cross-section of the combustion chamber and is open towards the axis of the combustion chamber, the pocket having guide surfaces 10, which cooperate with the edge region 14 or the fire box 13 in a manner which will be described further below. The guide surfaces 10 of the ring-shaped pocket 12 are connected in the example shown in the drawing to a cooling system 11 by which the temperature of the guide surfaces 10 can be brought to a predetermined value. Adjoining the narrow end of the upper chamber 7 is disposed another chamber 19 whose cross-section is widened by a wall 17. To the chamber 19 there is connected a conduit 23 which is part of the parallel circuit 4. Furthermore, in this chamber a burner arrangement 21 is so arranged that on the one hand the combustion gases produced by the open burner mix dependably with the gases fed through the conduit 23, while on the other hand the material being fired is protected from the open burner flames radiating against it.

Since the arrangement described can be operated also in the manner mentioned at the start, in which the fuel gases are fed to the largest cross-section of the combustion chamber alternately from the two sides, the narrow end of the lower combustion chamber section 8 also has a chamber which is widened by a wall 18 and to which there are connected the conduit 24 of the parallel circuit 4 and a burner device 22.

The two conduits 23, 24 of the parallel circuit can be connected for the alternate operation to the regenerator 2 via a reversing device 25.

The regenerator shown in the drawing operates continuously, with a flowable, heat-retainer mass 50, which is continuously circulated. The heat-retainer mass 50 is withdrawn from the regenerator through a corresponding air lock at 34 and discharged in the direction indicated by the arrow 51 and fed to an elevator 36, which returns the heat-retention mass 50 to an inlet 35 provided with a corresponding air lock at the top of the regenerator 2.

At approximately the midpoint of its height, the regenerator has a strong constriction 33 by which an upper regenerator chamber 31 is in communication with a corresponding lower regenerator chamber 32. The constriction is so dimensioned that the heatretention mass 50 can pass essentially without substantial resistance from the upper chamber 31 into the lower chamber 32, while the passage of the gases through the constriction 33 is strongly throttled.

At its upper end 43, the regenerator 2 has a connection for the removal of the combustion gases and at its lower end a feed connection 38 for return of the combustion gases, a corresponding grid tray conducting the heat-retention mass 50 being associated with the feed. By the connections described, the regenerator is connected in the main circuit 3 for the combustion gases. This main circuit has, in series with the regenerator 2, a blower 41 which assures the required pressure in the circulation system. Furthermore, a cooler 42 may also be provided in the main circuit in order to counteract any possible overheating. The main circuit also has a dust precipitator in the form of a cyclone 72, so that a continuous removal of the dust entrained by the heating and reaction gases is effected.

The parallel circuit 4 is connected via the connections 28 and 30 and the lines 26 and 27 via the regenerator 2 to the main circuit 3, the two connections lying directly above and below, respectively, the constriction 33 of the regenerator 2. Annular distributor sections 28a and 30a, respectively, can also be associated with the connections.

In the main circuit 3 the gases flow constantly in the direction indicated by the arrows. In the parallel circuit 4, behind the reversing device 25, the direction of flow indicated by the arrows can be reversed by means of the reversing device.

In order to make certain that the granulates present in the fire box 13, regardless of their position with respect to the edge, experience the same treatment, the fire box is designed in a particularly suitable manner. In cooperation with the above-described cooling of the guide surfaces 10 of the pockets 12 of the combustion chamber 13, it permits a very accurate control of the temperature in the outer region of the body produced by the ceramic bonding, as well as a desired temperature difference between said outer regions and the directly adjacent wall parts of the fire box which serves as form.

Referring now again to the drawings, and in particular to FIGS. 2 and 3 or 4 and 5, the fire box consists of a holding and guide frame 60 which consists of a steel casting with spheroidal graphite and has lower and upper guide surfaces 61 and 62. The latter are received completely in the pocket 12 of the combustion chamber 1 and either held in heat-transfer-improving contact with the guide surfaces 10 of the pocket 12, in which case the guide surfaces can be maintained at corresponding temperatures by the cooling channels which can be traversed by coolant, or else the supporting and guide frame is in turn provided with a cooler,

shown in dashed line in FIG. 2. The cooler consists, in the example, of a ring conduit 74 with connections 75 for the feeding and discharging of the coolant, and of an insulation 76 provided between the ring conduit 74 and the metal walls of the supporting and guide frame. In this embodiment, a valve device (not shown) can be provided in the connections 75 in case of liquid cooling, so that the cooler can be connected optionally or selectively to the corresponding sources of coolant.

By the direct cooling of the pocket walls, the holding and guide frames 60 can be maintained at about 400 C with a temperature of the material in the fire box of l000 to l200 C. No warping or deforming of the holding frame by the effect of temperature takes place.

box 13 in the pocket 12 from the movement around the fire box of the hot gases which are caused to act on the material.

For this purpose there is provided on the holding and .guide frame 60 a heat shield pointing towards the fired material 69; which shield consists of individual thin heat-shield plates 63 which are arranged alongside of each other with the formation of sufficiently large gaps 63a. The plates 63 are a considerable distance from the holding and guide frame 60 and are held on the latter of which may be so established by the provision of corresponding recesses 66, as shown in FIG. 2, that, with reference .to r the operating temperature, a predetermined resistance to the passage of heat is formed by the arms 64. The arms can be fastened in easily detachable manner by bent-off portions 65 to the holding and guide frame60, in which connection the nature and arrangement of the attachment of the heat-transfer resistarice can be effected, for instance, by intermediate layers of heat-insulating materials. The space between the heat-shield plates 63 and the, inside of the holding and guide frame 60 is filled with a heat-resistant heatinsulating material70, for instance aluminum silicate fiber. i

In the arrangement of FIGS. 4 and 5, a flow slot 73 is provided between the heat-shield plates 63 and the insulation 70 and serves, upon the heating of the form, for the rapid heating of the heat-shield plates 63 to a temperature approximately of the material or to 60C. below same. f

In FIG. 3 it is furthermore indicated that the heatshield plates 63 may consist of two layers of different material. The layer 6% consists advantageously of a reaction-sintered ceramic nonoxide, .while the layer 530 is made of cobalt steel containing more than 50 percent cobalt. The layer 63b may be applied directly or with leaving a gap in front of the layer 63c in the manner of a protective plate hung in front of same.

The bottom of the fire box 13 is formed of a grate which consists of individual grate bars 67, each of which is supported by corresponding shoulder extensions (see FIG. 2) on the heat-shield plates 63. Instead of the individual bars, grate elements or a grate can also be provided as a structural'unit.

The grate bars 67 which are preferably made of cobalt steel advisedly have a long rectangular crosssection and arearranged on edge. The dimensioning of the grate bars as well as their distance from each other in order to form the passage slots 71 are so selected, that the ratio of the slots to the total bottom area of the fire box 13 corresponds approximately to the total empty space of the granulate-forming material being fired 69. In this connection, values of this ratio within the magnitude indicated above have proven particularly advantageous. Thesupport member 68 in FIGS.

by narrow .arms 64, the heat-conducting cross-section 2 and Sindicates lower set ups of the heat shield plates,

which serve the purpose to support the rods of the bottom plates on the heat shield plates.

The fire box 13 described or the parts forming said fire box, respectively, are advisedly held by corresponding means also outside the combustion chamber 1' at temperatures, which do not differ by more than C. from the temperatures occurring in the combustion chamber 1.- By this temperature control, the result is obtained that the parts of the fire box are subjected only to slight alternating thermal stresses and the granulates which lie close to the parts of the fire boxes are not subjected to any different influence than those lyingspaced apart from the parts. of the form. In this way there is obtained an extremely great uniformity of the treatment of the charge of granulates in the fire box 13 and thus a high uniformity of the quality of the shaped bodies produced. It is only as a result of the design of the fire box described and the guidance thereof in the combustion chamber 1 that it is possible, fully to utilize the advantages of the precise control of the temperature and chemical composition of the combustion gases, as well as the possibility of rapidly changing these values during the firing process.

While I have disclosed several embodiments of the present invention, it is to be understood that these embodiments are given by example only and not in a limiting sense. i

I claim:

1. An apparatus I for manufacturing ceramically bonded shaped bodies from granulates of inflatable mineral materials, particularly clay, comprising a combustion chamber including two combustion chamber regions tapered down in opposite directions,

a firebox having a bottom grate and adapted .to be filled with granulates of inflatable material,

a mount and guide means for said fire box in substantially the plane of the joint largest cross-section of said combustion chamber and! moveable into and out of the latter, I

a conduit system connected to ,both ends of said burning chamber for guidingfuel and reaction gases in a circuit,

at least one burner device disposed in said circuit,

a reversing device for reversing the flow of said gases through said combustion chamber,

said mounting and guide means comprising a pocketshaped enlargement surrounding said combustion chamber and open to the axis of said chamber and having guide surfaceswithin said enlargement for reception of said fire box in said combustion chamber,

said fire box having an annular outerholding and guide frame engaging and directly supported and guided by said guide surfaces, said frame having inner surfaces, said fire box having effect of said heat and reaction cases and being connected heat-shield plate means divided into sections, narrow arms connecting said heat-shield plate means to said inner surfaces of said frame, said plate means limiting laterally and defining a filling space of said fire box, said arms forming heat flow resistances, said guide surfaces further protecting said frame against said gases.

2. The apparatus, as set forth in claim 1, wherein said pocket-shaped enlargement includes ter and supported by said holding and guide frame.

5. The apparatus as set forth in claim 4, wherein said shield-plates comprise a plurality of layersof different materials of high temperature-resistance, and cobalt steel.

6. The apparatus, as set forth'in claim 4, wherein said shield plates comprise a plurality of layers, one of which consists of high heat resistance ceramic non-oxide and one other layer consists of cobaltsteel.

'7. The apparatus, as set forth in claim 6, wherein said ceramic-non-oxide is a reaction-sintered material selected from the group consisting of a nitride, a carbide, and a boride.

8. The apparatus, as set forth in claim 5, wherein said heat shield plate means defines a space between itself and said supporting-andg ide-frame, and

said space is filled at least 1 in part with a heatinsulating material.

9. The apparatus, as set forth in claim 8, wherein said heat-insula-ting material comprises aluminum silicate fibers.

10. The apparatus, as set forth in claim 1, wherein the bottom of said fire box comprises grate bars which are supported on said heat shield plate means and have selectively the form of individual bars, grate elements and a structural unit includin a plurality of bars.

11. The apparatus, as set forth in claim 10, wherein the ratio of the open surface of the total bottom surface of said fire box is approximately equal to the relative empty space of the filling of material to be fired.

12. The apparatus, as set forth in claim 11, wherein said ratio of open surface to the total bottom surface is between about 0.26:1 and 0.46:1.-

13. The apparatus, as set forth in claim 11, wherein the ratio of open surface to total bottom surface is between 0.36:1 and 0.40:1. 

1. An apparatus for manufacturing ceramically bonded shaped bodies from granulates of inflatable mineral materials, particularly clay, comprising a combustion chamber including two combustion chamber regions tapered down in opposite directions, a fire box having a bottom grate and adapted to be filled with granulates of inflatable material, a mount and guide means for said fire box in substantially the plane of the joint largest cross-section of said combustion chamber and moveable into and out of the latter, a conduit system connected to both ends of said burning chamber for guiding fuel - and reaction - gases in a circuit, at least one burner device disposed in said circuit, a reversing device for reversing the flow of said gases through said combustion chamber, said mounting and guide means comprising a pocket-shaped enlargement surrounding said combustion chamber and open to the axis of said chamber and having guide surfaces within said enlargement for reception of said fire box in said combustion chamber, said fire box having an annular outer holding - and guide frame engaging and directly supported and guided by said guide surfaces, said frame having inner surfaces, said fire box having effect of said heat - and reaction - cases and being connected heat-shield plate means divided into sections, narrow arms connecting said heat-shield plate means to said inner surfaces of said frame, said plate means limiting laterally and defining a filling space of said fire box, said arms forming heat flow resistances, said guide surfaces further protecting said frame against said gases.
 2. The apparatus, as set forth in claim 1, wherein said pocket-shaped enlargement includes a cooling system means operatively connected with said guide surfaces for cooling the latter.
 3. The apparatus, as set forth in claim 1, wherein said holding - and guide - frame of said fire box is equipped with cooling means through which a coolant passes for cooling said frame.
 4. The apparatus as set forth in claim 2, wherein said heat shield plate means comprises a plurality of individual shield - plates forming gaps between the latter and supported by said holding - and guide - frame.
 5. The apparatus as set forth in claim 4, wherein said shield-plates comprise a plurality of layers of different materials of high temperature-resistance, and cobalt steel.
 6. The apparatus, as set forth in claim 4, wherein said shield plates comprise a plurality of layers, one of which consists of high heat resistance ceramic - non-oxide and one other layer consists of cobalt-steel.
 7. The apparatus, as set forth in claim 6, wherein said ceramic-non-oxide is a reaction-sintered material selected from the group consisting of a nitride, a carbide, and a boride.
 8. The apparatus, as set forth in claim 5, wherein said heat shield plate means defines a space between itself and said supporting-and guide-frame, and said space is filled at least in part with a heat-insulating material.
 9. The apparatus, as set forth in claim 8, wherein said heat-insula-ting material comprises aluminum silicate fibers.
 10. The apparatus, as set forth in claim 1, wherein the bottom of said fire box comprises grate bars which are supported on said heat shield plate means and have selectively the form of individual bars, grate elements and a structural unit including a plurality of bars.
 11. The apparatus, as set forth in claim 10, wherein the ratio of the open surface of the total bottom surface of said fire box is approximately equal to the relative empty space of the filling of material to be fired.
 12. The apparatus, as set forth in claim 11, wherein said ratio of open surface to the total bottom surface is between about 0.26:1 and 0.46:1.
 13. The apparatus, as set forth in claim 11, wherein the ratio of open surface to total bottom surface is between 0.36:1 and 0.40:1. 